J
John S
Guest
On 11/25/2013 4:16 AM, Rajdeep shaktawat wrote:
This is an ad by deep tawat?
This is an ad by deep tawat?
J
John Fields
Guest
On Mon, 25 Nov 2013 04:17:14 -0800 (PST), Rajdeep shaktawat
<accurate.rajdeep@gmail.com> wrote:
---
No one asked for a recommendation, and unsolicited advertisements
are unwelcome here, so your out-of-the-blue post is nothing but SPAM
and disrespectful of the wishes of the members of this group.
<accurate.rajdeep@gmail.com> wrote:
---
No one asked for a recommendation, and unsolicited advertisements
are unwelcome here, so your out-of-the-blue post is nothing but SPAM
and disrespectful of the wishes of the members of this group.
K
Kennedy
Guest
On 25/11/2013 8:17 PM, Rajdeep shaktawat wrote:
This is an ad by deep twat!
This is an ad by deep twat!
J
John Larkin
Guest
On Mon, 25 Nov 2013 02:16:00 -0800 (PST), Rajdeep shaktawat
<accurate.rajdeep@gmail.com> wrote:
>There are also so many training centers who teaches to make such industrial things. And many manufacturer to such industrial instruments like temperature sensors and Thermal Imaging Camera such as, http://accuratesensors.com/thermal-imager-thermeye160.html
We have a FLIR E45 with a close-up lens. It can resolve the hot spot on an 0603
resistor. Many of the cheap thermal IR imagers are not very good with
electronics.
Anybody care to post some thermal images of PC boards? I'd be interested in
knowing if any less expensive imagers are good with electronics. The FLIR is
great but it cost $12K.
https://dl.dropboxusercontent.com/u/53724080/Thermal/IR_Board.jpg
https://dl.dropboxusercontent.com/u/53724080/Thermal/IR_ADC.jpg
https://dl.dropboxusercontent.com/u/53724080/Thermal/NEC_dual_transistor.jpg
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
<accurate.rajdeep@gmail.com> wrote:
>There are also so many training centers who teaches to make such industrial things. And many manufacturer to such industrial instruments like temperature sensors and Thermal Imaging Camera such as, http://accuratesensors.com/thermal-imager-thermeye160.html
We have a FLIR E45 with a close-up lens. It can resolve the hot spot on an 0603
resistor. Many of the cheap thermal IR imagers are not very good with
electronics.
Anybody care to post some thermal images of PC boards? I'd be interested in
knowing if any less expensive imagers are good with electronics. The FLIR is
great but it cost $12K.
https://dl.dropboxusercontent.com/u/53724080/Thermal/IR_Board.jpg
https://dl.dropboxusercontent.com/u/53724080/Thermal/IR_ADC.jpg
https://dl.dropboxusercontent.com/u/53724080/Thermal/NEC_dual_transistor.jpg
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
J
John Miles, KE5FX
Guest
On Monday, November 25, 2013 7:26:02 AM UTC-8, John Larkin wrote:
Someone recently found that the 80x60 E4 model that sells for US $1000 has the same sensor hardware as the 320x240 E8 model that sells for $6000. Google 'FLIR E4 hack' for pointers.
Additionally, it turns out that ZnSe lenses for laser cutters are useful for macro work with IR cameras. This shot was taken with a $30 Chinese lens ( http://cgi.ebay.com/321078811086 ) in front of my tweaked E4:
http://www.ke5fx.com/flirtest.pdf
Registration between the visible and IR cameras isn't ideal in closeups, but it's still quite usable. The smaller resistors are 1206 parts on this board but you wouldn't have any trouble identifying 0402s.
The E4 is actually a pretty nice camera for US $1000 even at its native 80x60 resolution. Have to assume they will 'fix' the hack at some point, of course.
-- john
Someone recently found that the 80x60 E4 model that sells for US $1000 has the same sensor hardware as the 320x240 E8 model that sells for $6000. Google 'FLIR E4 hack' for pointers.
Additionally, it turns out that ZnSe lenses for laser cutters are useful for macro work with IR cameras. This shot was taken with a $30 Chinese lens ( http://cgi.ebay.com/321078811086 ) in front of my tweaked E4:
http://www.ke5fx.com/flirtest.pdf
Registration between the visible and IR cameras isn't ideal in closeups, but it's still quite usable. The smaller resistors are 1206 parts on this board but you wouldn't have any trouble identifying 0402s.
The E4 is actually a pretty nice camera for US $1000 even at its native 80x60 resolution. Have to assume they will 'fix' the hack at some point, of course.
-- john
J
John Larkin
Guest
On Mon, 25 Nov 2013 13:15:16 -0800 (PST), "John Miles, KE5FX" <jmiles@gmail.com>
wrote:
That's impressive, nice resolution.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
wrote:
That's impressive, nice resolution.
--
John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
G
Greegor
Guest
On Monday, November 25, 2013 5:49:15 PM UTC-6, Maynard A. Philbrook Jr. wrote:
Clapper Caper
http://www.youtube.com/watch?v=cjquGpmgwOo
Clapper Caper
http://www.youtube.com/watch?v=cjquGpmgwOo
G
Greegor
Guest
Jeff Liebermann wrote:
That would be a one hell of a candid camera
gag to play on the city building inspectors.
I'd LOVE to see their faces when somebody
demonstrates THAT to them!
I can see it now, Berkley Trilene 40 Lb test
monofilament strung up into the attic and
down into another room! LOL
That would be a one hell of a candid camera
gag to play on the city building inspectors.
I'd LOVE to see their faces when somebody
demonstrates THAT to them!
I can see it now, Berkley Trilene 40 Lb test
monofilament strung up into the attic and
down into another room! LOL
R
Robert Baer
Guest
John Larkin wrote:
They refuse to remove it unless you are the FED.
But...how the F can one ELIMINATE the gd FLIR logo?
They refuse to remove it unless you are the FED.
J
John Larkin
Guest
On Tue, 26 Nov 2013 10:20:27 -0800, Robert Baer
<robertbaer@localnet.com> wrote:
Crop the image!
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
<robertbaer@localnet.com> wrote:
Crop the image!
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
G
Greegor
Guest
I poked around and found huge list
of X10 items that are discontinued.
http://www.smarthomeusa.com/ShopByManufacturer/X-10-Pro/
and more convincing:
http://www.smarthomeusa.com/Shop/Books/
Home Automation Books & Magazines
No products are currently available from this category.
Unavailable/discontinued items are listed below for your reference.
[ list of books ]
of X10 items that are discontinued.
http://www.smarthomeusa.com/ShopByManufacturer/X-10-Pro/
and more convincing:
http://www.smarthomeusa.com/Shop/Books/
Home Automation Books & Magazines
No products are currently available from this category.
Unavailable/discontinued items are listed below for your reference.
[ list of books ]
R
Robert Baer
Guest
P E Schoen wrote:
do the job; use of the almost-smallest looks-good-on-paper size may
result in cracked cores and split shrink.
Word of warning regarding heatshrink: use the largest size that will
do the job; use of the almost-smallest looks-good-on-paper size may
result in cracked cores and split shrink.
P
P E Schoen
Guest
"Robert Baer" wrote in message news:8qhlu.262216$eE7.228412@fx21.iad...
Thanks for the advice. The heat shrink tape I found at McMaster is only
0.002" thick and is probably something like the shrink-wrap used for
shipping items on pallets, so I don't think it is very strong. Of course it
would be a good idea to use several wraps. It seems like a good deal at $13
for 300 ft of 3/4" wide tape. I plan to order some and try it.
Paul
Thanks for the advice. The heat shrink tape I found at McMaster is only
0.002" thick and is probably something like the shrink-wrap used for
shipping items on pallets, so I don't think it is very strong. Of course it
would be a good idea to use several wraps. It seems like a good deal at $13
for 300 ft of 3/4" wide tape. I plan to order some and try it.
Paul
J
Jan Panteltje
Guest
On a sunny day (Tue, 26 Nov 2013 22:49:19 -0500) it happened "P E Schoen"
<paul@peschoen.com> wrote in <l73q4c$jt6$1@dont-email.me>:
Hi Paul,
I have used cable ty ribbons in the past with success.
You can put those in series too for bigger cores, and precisely adjust the strength,
and or even connect the who assembly to the PCB using a few holes.
Normal procefure would be a couple of long screws and a clamp plate.
<paul@peschoen.com> wrote in <l73q4c$jt6$1@dont-email.me>:
Hi Paul,
I have used cable ty ribbons in the past with success.
You can put those in series too for bigger cores, and precisely adjust the strength,
and or even connect the who assembly to the PCB using a few holes.
Normal procefure would be a couple of long screws and a clamp plate.
C
Chris Jones
Guest
On 27/11/2013 05:22, John Larkin wrote:
I believe the "other" hack lets you do that too, and the manual
temperature spans and stuff. (I think it makes the logo transparent.) I
have only been game to increase the resolution so far. Read the eevblog
forum for the details if you're interested.
Chris
I believe the "other" hack lets you do that too, and the manual
temperature spans and stuff. (I think it makes the logo transparent.) I
have only been game to increase the resolution so far. Read the eevblog
forum for the details if you're interested.
Chris
T
Tim Williams
Guest
Waveform calculator:
http://schmidt-walter.eit.h-da.de/smps_e/smps_e.html
If you don't know what you're doing as far as transformer specs, leave
those fields alone (Lp, N2/N1, etc.). If you do know, you can enter them,
hit Calculate, and it'll show what will happen with a
(transformer/inductor) of those specs.
Doesn't have push-pull (which is going to be best at a relatively low
voltage), but you can play with a half or full bridge and adjust the
primary volts, amps and turns respectively (PP has double the primary of
H-bridge, which has twice the turns and half the amps of half bridge).
Even has tables of core types; you should be able to enter parameters of
your own core to see suitability as well.
My website has a rather old article that I should rewrite for more clarity
and stuff;
http://webpages.charter.net/dawill/tmoranwms/Elec_Magnetics.html
I think it still covers forward converter style transformer design, which
is handy here (you probably wouldn't choose a flyback, let alone a buck,
for these voltages, heheh).
In short: core size depends on how many turns you can get around it, the
peak flux density of the design, and the voltage and applied frequency:
N = Vsq / (4 * F * Bmax * Ae)
N = number of turns required for a given winding
Vsq = square wave peak voltage applied to that winding
F = frequency (50% duty cycle, no DC)
Ae = cross sectional area of the core (i.e., area of the section the turns
are wrapped around)
Bmax = maximum design flux density
For laminated iron at 50/60Hz, use Bmax = 1.2T or so. For ferrite under
100kHz or so, use 0.3T, or less at higher frequencies where losses bite
more (depends on material).
Or, rearrange the equation by algebra to solve for whichever parameter you
need (e.g., you've set up a coil and want to know what Bmax it's actually
achieving).
Note this doesn't depend on gap; transformer action assumes gap is zero
and permeability infinite. Other issues (like DC bias, startup
transients, overload behavior, etc.) may affect the choice of gap (if
any).
This is one of the more important magnetic relations; if you don't know
anything about magnetism, this should be helpful, and the rest is geometry
and guessing how much copper can actually fit around the core.
Tim
--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com
"P E Schoen" <paul@peschoen.com> wrote in message
news:l73q4c$jt6$1@dont-email.me...
I want to make a DC-DC converter for 48 VDC to about 300 VDC at a
continuous
power of about 800W to drive a 1 to 2 HP three phase induction motor. I
have
some E55 cores and coilformers which should do the job, and also some
E47/20/15 which might work OK. The E55 is an Epcos type N27 and the E47 is
probably the same.
http://www.mouser.com/ds/2/136/e_47_20_16-75097.pdf
http://www.mouser.com/ds/2/136/e_55_28_21-73714.pdf
I found a website that shows a simple procedure to determine the turns
required for a transformer in a half-bridge topology using three
capacitors.
I plan to use the same circuit but not use the additional series capacitor
and instead use two 20 uF 100 VAC PP capacitors in series across the DC
bus
and the center to one end of the primary.
http://tahmidmc.blogspot.com/2013/02/ferrite-transformer-turns-calculation_22.html
The LTSpice for the basic circuit is on my server:
http://enginuitysystems.com/pix/48V-320V_DCDC_HalfBridge_2Cap.asc
I made a spreadsheet to automate the selection process and for the E55
core
and 50 kHz it came up with 23 turns of #8 AWG for the primary at 33 amps
and
144 turns of #16 for the secondary at 5.3 amps. It appears to have 8 watts
of ferrite losses and about 6 watts primary and secondary copper losses
for
total efficiency of about 97%.
Here is the (OpenOffice) spreadsheet. Please have a look and see if it is
at
least close to being accurate:
http://enginuitysystems.com/files/Ferrite_Transformer.ods
Another question I have is if would be helpful to use heat shrink tape to
compress the ferrite halves:
http://www.mcmaster.com/#heat-shrink-tape/=pjzuzt
And, finally, I think it would be good to use Litz wire for this. I found
some that seems to be a good deal:
http://www.ebay.com/itm/370951676185
Thanks,
Paul
http://schmidt-walter.eit.h-da.de/smps_e/smps_e.html
If you don't know what you're doing as far as transformer specs, leave
those fields alone (Lp, N2/N1, etc.). If you do know, you can enter them,
hit Calculate, and it'll show what will happen with a
(transformer/inductor) of those specs.
Doesn't have push-pull (which is going to be best at a relatively low
voltage), but you can play with a half or full bridge and adjust the
primary volts, amps and turns respectively (PP has double the primary of
H-bridge, which has twice the turns and half the amps of half bridge).
Even has tables of core types; you should be able to enter parameters of
your own core to see suitability as well.
My website has a rather old article that I should rewrite for more clarity
and stuff;
http://webpages.charter.net/dawill/tmoranwms/Elec_Magnetics.html
I think it still covers forward converter style transformer design, which
is handy here (you probably wouldn't choose a flyback, let alone a buck,
for these voltages, heheh).
In short: core size depends on how many turns you can get around it, the
peak flux density of the design, and the voltage and applied frequency:
N = Vsq / (4 * F * Bmax * Ae)
N = number of turns required for a given winding
Vsq = square wave peak voltage applied to that winding
F = frequency (50% duty cycle, no DC)
Ae = cross sectional area of the core (i.e., area of the section the turns
are wrapped around)
Bmax = maximum design flux density
For laminated iron at 50/60Hz, use Bmax = 1.2T or so. For ferrite under
100kHz or so, use 0.3T, or less at higher frequencies where losses bite
more (depends on material).
Or, rearrange the equation by algebra to solve for whichever parameter you
need (e.g., you've set up a coil and want to know what Bmax it's actually
achieving).
Note this doesn't depend on gap; transformer action assumes gap is zero
and permeability infinite. Other issues (like DC bias, startup
transients, overload behavior, etc.) may affect the choice of gap (if
any).
This is one of the more important magnetic relations; if you don't know
anything about magnetism, this should be helpful, and the rest is geometry
and guessing how much copper can actually fit around the core.
Tim
--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com
"P E Schoen" <paul@peschoen.com> wrote in message
news:l73q4c$jt6$1@dont-email.me...
I want to make a DC-DC converter for 48 VDC to about 300 VDC at a
continuous
power of about 800W to drive a 1 to 2 HP three phase induction motor. I
have
some E55 cores and coilformers which should do the job, and also some
E47/20/15 which might work OK. The E55 is an Epcos type N27 and the E47 is
probably the same.
http://www.mouser.com/ds/2/136/e_47_20_16-75097.pdf
http://www.mouser.com/ds/2/136/e_55_28_21-73714.pdf
I found a website that shows a simple procedure to determine the turns
required for a transformer in a half-bridge topology using three
capacitors.
I plan to use the same circuit but not use the additional series capacitor
and instead use two 20 uF 100 VAC PP capacitors in series across the DC
bus
and the center to one end of the primary.
http://tahmidmc.blogspot.com/2013/02/ferrite-transformer-turns-calculation_22.html
The LTSpice for the basic circuit is on my server:
http://enginuitysystems.com/pix/48V-320V_DCDC_HalfBridge_2Cap.asc
I made a spreadsheet to automate the selection process and for the E55
core
and 50 kHz it came up with 23 turns of #8 AWG for the primary at 33 amps
and
144 turns of #16 for the secondary at 5.3 amps. It appears to have 8 watts
of ferrite losses and about 6 watts primary and secondary copper losses
for
total efficiency of about 97%.
Here is the (OpenOffice) spreadsheet. Please have a look and see if it is
at
least close to being accurate:
http://enginuitysystems.com/files/Ferrite_Transformer.ods
Another question I have is if would be helpful to use heat shrink tape to
compress the ferrite halves:
http://www.mcmaster.com/#heat-shrink-tape/=pjzuzt
And, finally, I think it would be good to use Litz wire for this. I found
some that seems to be a good deal:
http://www.ebay.com/itm/370951676185
Thanks,
Paul
J
Jeff Liebermann
Guest
On Tue, 26 Nov 2013 14:42:27 -0800 (PST), Greegor
<greegor47@gmail.com> wrote:
Locally, the building inspectors are mostly failed independent
contractors, job creation beneficiaries, or amateur attorneys. While
many are amazingly competent, most have an agenda and a retaliatory
attitude. I've learned from experience not to mess with them as they
are quite capable of turning a minor remodel into a very expensive
house reconstruction project.
Personally, I would not like to see them at all.
Full disclosure: I actually built the string and wall switch trick
when I was about 10 years old. That included drilling a hole in the
Bakelite lever. The light switch to my room was mislocated opposite
the doorway due to a remodel. After watching a few horror movies at
the theater, I was afraid of the dark and wanted the switch moved to
closer to the door. Rewiring wasn't possible, so I contrived the
string trick. The initial problem was that I only used one string,
which only worked to turn on the light. My father was suitably
impressed and fabricated some eye hooks with 6-32 threads. He also
supplied a proper ladder as he suspected that piling two chairs on top
of my bed was not a stable arrangement. I vaguely recall it lasted
for about a year before the string broke. Note that the 1950's wall
switches required far more force to actuate than todays switches. I
used stronger "box string", not kite string. I didn't know about
3-way switches until I was much older. Since there was nothing
structural or electrical involved, the arrangement would probably pass
a code inspection.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
<greegor47@gmail.com> wrote:
Locally, the building inspectors are mostly failed independent
contractors, job creation beneficiaries, or amateur attorneys. While
many are amazingly competent, most have an agenda and a retaliatory
attitude. I've learned from experience not to mess with them as they
are quite capable of turning a minor remodel into a very expensive
house reconstruction project.
Personally, I would not like to see them at all.
Full disclosure: I actually built the string and wall switch trick
when I was about 10 years old. That included drilling a hole in the
Bakelite lever. The light switch to my room was mislocated opposite
the doorway due to a remodel. After watching a few horror movies at
the theater, I was afraid of the dark and wanted the switch moved to
closer to the door. Rewiring wasn't possible, so I contrived the
string trick. The initial problem was that I only used one string,
which only worked to turn on the light. My father was suitably
impressed and fabricated some eye hooks with 6-32 threads. He also
supplied a proper ladder as he suspected that piling two chairs on top
of my bed was not a stable arrangement. I vaguely recall it lasted
for about a year before the string broke. Note that the 1950's wall
switches required far more force to actuate than todays switches. I
used stronger "box string", not kite string. I didn't know about
3-way switches until I was much older. Since there was nothing
structural or electrical involved, the arrangement would probably pass
a code inspection.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
J
Jim Thompson
Guest
On Wed, 27 Nov 2013 08:14:12 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:
[snip]
One trick I learned when I went to get the permit to plumb 100 feet of
2.5" gas line to my pool heater... I played dumb and had the guy at
the permit counter draw up how I should do it
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
wrote:
[snip]
One trick I learned when I went to get the permit to plumb 100 feet of
2.5" gas line to my pool heater... I played dumb and had the guy at
the permit counter draw up how I should do it
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice
480)460-2350 Fax: Available upon request | Brass Rat || E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Guest
On Wed, 27 Nov 2013 09:32:51 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
I've found that that strategy ("How do you want this done?") works,
but can be expensive. I built a garage, many moons ago. The
inspector made me put an 8" H-beam across the front, a steel-fire door
with a steel frame, and sheetrock the entire interior. He added over
a grand (>10%) to the cost of the project.
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
On Wed, 27 Nov 2013 08:14:12 -0800, Jeff Liebermann <jeffl@cruzio.com
wrote:
[snip]
Locally, the building inspectors are mostly failed independent
contractors, job creation beneficiaries, or amateur attorneys. While
many are amazingly competent, most have an agenda and a retaliatory
attitude. I've learned from experience not to mess with them as they
are quite capable of turning a minor remodel into a very expensive
house reconstruction project.
[snip]
One trick I learned when I went to get the permit to plumb 100 feet of
2.5" gas line to my pool heater... I played dumb and had the guy at
the permit counter draw up how I should do it
I've found that that strategy ("How do you want this done?") works,
but can be expensive. I built a garage, many moons ago. The
inspector made me put an 8" H-beam across the front, a steel-fire door
with a steel frame, and sheetrock the entire interior. He added over
a grand (>10%) to the cost of the project.
P
P E Schoen
Guest
"Tim Williams" wrote in message news:l74saa$guj$1@dont-email.me...
The calculator is very helpful. I found that the E55/28/21 is a bit too
small for 750W (300V 2.5A) but is very good for 625W (250V 2.5A). This is
for 48-56V in and 50 kHz. However, it does not show the material of the
core, although maybe I can look up the Siemens part. The N27 I have appears
to be better for low frequency (25 kHz) while the N87 is characterized at
100 kHz.
The calculator shows 8 turns primary and 88 turns secondary, while my
spreadsheet shows 23 and 144. I may not have properly calculated the ratios
for the topology, and I used 1610 Gauss instead of 0.2 Tor. Making that
adjustment, I get 11T/57T, but the secondary should really be twice that.
Then the ratio is 10.4 which compares to 11 for the calculator. I should
have used half the input voltage for the actual primary voltage with this
topology.
I suppose I should actually build one of these transformers and take
measurements.
What do you think about the Litz wire? It is equivalent to #18 AWG so it
might be OK for the secondary, and the primary would need at least 8 or 10
in parallel. #18 should be good for 4.7 amps at 342 CM/A or 5.8 A/mm^2. The
calculator uses 3 A/mm^2, and if I use 600 CM/A or 3.3 A/mm^2, #18 is good
for 2.7 A, and 8 in parallel will give 22 amps while I need 33. So probably
12 in parallel would be needed, or else allow more temperature rise. I will
probably need about the same total length of wire for primary and secondary,
and I come up with about 20 ft. I think $35-$50 for 300 ft is a pretty good
deal.
Thanks,
Paul
The calculator is very helpful. I found that the E55/28/21 is a bit too
small for 750W (300V 2.5A) but is very good for 625W (250V 2.5A). This is
for 48-56V in and 50 kHz. However, it does not show the material of the
core, although maybe I can look up the Siemens part. The N27 I have appears
to be better for low frequency (25 kHz) while the N87 is characterized at
100 kHz.
The calculator shows 8 turns primary and 88 turns secondary, while my
spreadsheet shows 23 and 144. I may not have properly calculated the ratios
for the topology, and I used 1610 Gauss instead of 0.2 Tor. Making that
adjustment, I get 11T/57T, but the secondary should really be twice that.
Then the ratio is 10.4 which compares to 11 for the calculator. I should
have used half the input voltage for the actual primary voltage with this
topology.
I suppose I should actually build one of these transformers and take
measurements.
What do you think about the Litz wire? It is equivalent to #18 AWG so it
might be OK for the secondary, and the primary would need at least 8 or 10
in parallel. #18 should be good for 4.7 amps at 342 CM/A or 5.8 A/mm^2. The
calculator uses 3 A/mm^2, and if I use 600 CM/A or 3.3 A/mm^2, #18 is good
for 2.7 A, and 8 in parallel will give 22 amps while I need 33. So probably
12 in parallel would be needed, or else allow more temperature rise. I will
probably need about the same total length of wire for primary and secondary,
and I come up with about 20 ft. I think $35-$50 for 300 ft is a pretty good
deal.
Thanks,
Paul